There are currently two general systems for operating cameras during cinematography. The first and oldest system is a manual control of the camera and its support platform. Manual control of the camera is provided by a cameraman, and manual control of the support platform is provided by a grip. Before taping a scene, a director instructs actors to move about the set and speak, and perform specified actions. The director also ensures that the scenery, props, and lighting are placed on the set according to his instructions. The director also instructs a camera crew to film the action on the set during a take and capture the action and/or scenery from various viewpoints, with specified camera frames, and to follow the action with specified movements of the camera. The view point is defined by the relationship of the camera to the subject being filmed, and is determined by the location of the support platform and position of any booms or hoist mechanisms used to support the camera. The camera frames are defined by the relationship of the subject being filmed to the entire size of the scene filmed (closeup, portrait, group or landscape are terms that are sometimes used to describe various camera frames). The camera parameters include such things as the pan angle, the tilt angle, and the rotation angle (i.e., spatial attitude of the camera itself) and zoom, aperture, focus and focal length (i.e. lens system attributes). The action is set in motion and is filmed by camera crew, and during filming, the grip will move the support platform to hit the planned view points and the camera operator will adjust the camera parameters to obtain the desired frames follow the action with the specified movements (at the same time, the actors on the set will be moving, speaking and acting according to their own directions).
This is a highly interactive process, and the camera operator and grip must react to variances between the planned action and what actually goes on during each take, and variances between the actual action from take to take. In some situations, this method of filming becomes extremely difficult, and requires great experience and talent for the camera operator and the grip. For example, if the camera support platform is a crane with the camera supported on a remotely controlled camera head, the manual operation of the camera and lens parameters is best performed through remote control, from a remote control panel located at the base of the crane. The pan, tilt and rotation angles are operated by servo-motors at the remote head which adjust these parameters in response to operation of remote control hand wheels. Likewise, the lens system attributes (zoom, focus, etc.) are operated by servo-motors attached to the camera controls, and the servo-motors are operated by input devices on the remote control panel. The remote control panel may consist of a single control panel with controls for all parameters, or separate camera attitude control panel and camera lens system attribute control panel. A typical remote head has hand wheels for adjusting the camera pan, tilt, and rotation.
For a given live action scene, the director may desire viewpoints and camera frames which require large motions of the camera platform and fast motions of some or all of the camera parameters. The number and variety of combinations of such movement are limited only by the creativity of the cinematographer and director. The grip may be required to swing the boom of a camera crane quickly, while the camera operator may at the same time be required to quickly back-pan while slowly adjusting the camera tilt. Thus, for a single operator to adjust these parameters requires simultaneous adjustment and rotation of the hand wheels, but at varying speeds and directions for each hand wheel. This is quite difficult, akin to rubbing your tummy while patting your head, and maybe hopping up and down, where the patting occurs at one speed, the rubbing occurs at another speed, and the hopping occurs at yet another speed.
Another way to film a scene is through the use of computer operated motion control systems. These systems are ideal for reproducing exactly the same camera movement over and over again, which is desirable in special effects creation. The ability to film the exact same sequence, over and over again, helps cinematographers and producers produce special effects in which many images are layered on top of each other. Examples of the special effects created with motion control systems are the various space battle scenes in which numerous spaceships fly about on diverse flight paths while the camera follows one of the space ships. This type of special effect is created by filming a first scene in which the model central ship flies through a model stage while the camera follows the ship as desired. After this first scene is filmed, another scene is taped in which a model second ship flies through the model stage, and it is filmed by the camera while the camera proceeds along the exact same pathway to capture this second scene. The two films are then layered together to make a single film showing both ships together. Any number of ships may be added to the scene by taping additional ships while the camera repeats its path exactly for every take. In order for the movement of the various ships to appear responsive to each other, and to permit accurate overlays, the different films must be synchronized. Battle scenes such as the spectacular Star Wars dog fight between Luke Skywalker and Darth Vader in the trench of the Death Star were created using this type of system.
Typical motion control systems, such as those used by Industrial Light and Magic, and those produced by Mark Roberts Motion Control or Christopher Nibley Cinematographers, control every parameter of both the crane and camera operation. The movement of the crane along a track, the speed of the crane movement, the boom tilt, boom extension and crane rotation, as well as camera pan, tilt, rotation, zoom, aperture and focal length are all controlled by the computer. In these systems, a key frame method may be used to establish the several points along the desired path of the crane and camera. The crane is moved to a number of key positions, the camera attitude adjusted to a number of corresponding key attitudes, and the camera controls adjusted to obtain a key frame defined by the camera parameters. These key frames are selected by the director, and the key frame is defined by certain predetermined field of view, focal length, focus and orientation of the scene on the film. This key frame corresponds to the zoom, camera attitude, and camera position and crane position used to view the key frame. In the key frame motion control system, the system memorizes all the parameters of the key frame, and receives input from the system operator on the desired predetermined time to hit each key frame. When the system is instructed to start a take, it moves the camera to the key frames at the predetermined times. The camera may interpolate movement between the key frames to ensure a smooth trajectory of the camera between key frames. The key frames are hit at the same time in every take, and we refer this as a synchronized system because the key frames and all other frames are strictly tied to a master clock to ensure that the camera movement proceed not only through the same points, but also at the same pace, on every take.
These motion control systems completely eliminate operator input during the take. The advantage of this system is that it can repeat complicated camera movements very precisely, and many times over, with no deviation in the movement of the camera from one take to the next. On the other hand, the system does not permit modification of the camera movement during the take, because it is not intended for use in live action where it is desirable to modify the camera movement from the predetermined camera movement during the take.
For filming of many live action scenes, manual manipulation of the camera is exceedingly difficult. The artistically desired pace and movement of the camera between viewpoints may require extremely rapid manipulation of the camera controls. While a talented cameraman may be able get the shot, the need to film several takes of the same scene due to limitations in the camera operator's work, the grips work, the actors' performance and the motion of other subjects such as vehicles and animals increases the workload, and a system that provides assistance to the cameraman facilitates production. Use of a motion control system as described above is not a feasible solution, because the camera movement and operation is fixed by the system and cannot be altered to account for variations in the performance as a cameraman can.